Questions tagged [matching]

A matching (aka **Independent Edge Set**) in a simple graph is the set of pairwise non-adjacent edges i.e. no two edges have common vertex.

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60 views

Hardness result for online matching

Currently studying the following paper: "Fair Allocation in Online Markets" - Gollapudi and Panigrahi 2014 In which they present Theorem 2 as a hardness result for online maxmin matchings (...
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35 views

How to match two point sets to minimize total distance?

Let's say we have two sets $X = \{x_1, \ldots, x_n\} \subset \mathbb R^d$, $Y =\{y_1,\ldots, y_n\} \subset \mathbb R^d$, how can we find a permutation $\pi$ such that $$D = \sum_{i=1}^n d(x_i, y_{\pi(...
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20 views

Three dimensional matching expressed as SAT

The posting in the website Embedding SATISFIABILITY into 3-DIMENSIONAL MATCHING seeks $3SAT$ as a $3$ dimensional matching instance. I am looking to solve the converse problem. How to solve three ...
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Algorithm to pair respondents based on differences in answers to survey

I am having the following problem: I have asked a number of people 7 different binary questions. I now want to pair my respondents based on how different their answers to the questions were. The goal ...
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11 views

Generic real-time message/event matching engine

I'm looking for methods (any kind of combinations of algorithms & corresponding data structures) that can be used as a generic matching engine in case of arbitrary message/event types. Let me ...
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33 views

Algo to match students to universities (only students choose & rank)

I'm trying to develop an algorithm in Ruby to allocate one university to each student of a list. As opposed to Gale-Shapley algorithm, universities do no choose nor rank students; only students make a ...
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1answer
46 views

What is the comparator circuit?

The standard circuits $AC^i$, $NC^i$ are constructed using $AND$, $OR$ and $NOT$ of various fan-ins, fan-outs and depths. What is the comparator gate constituted from? Structurally why is it believed $...
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20 views

What is the depth of comparator circuit required in Gale Shapely and STCONN?

Stable matching problem and $STCONN$ can be solved using comparator circuits (refer https://arxiv.org/abs/1208.2721). What is the depth of the $CC$ circuit necessary for stable matching? Is it in $CC^...
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Subgraph isomorphism index/precomputation

I'm currently working on problem in which a set of graphs $T=\{t_1,\dots,t_n\}$ is given and fixed. Given a graph $m$ I want to check which of the $t_i$ are subgraphs of it, as quick as possible. Is ...
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34 views

Hardness of multiplicative vs. additive approximation

Chlebik and Chlebikova prove that the problem "maximum 3-dimensional matching" is NP-hard to approximate within a multiplicative factor of $95/94$. This means that, unless $P=NP$, there is ...
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50 views

a lower bound for the maximum fraction of matchings not containing an edge

I am trying to prove the following statement (from book, page 317): Let $G(A,B,E)$ be a bipartite graph, where $A$ and $B$ are the two disjoint sets of vertices s.t. $|A|=|B|=n$. Let the number of ...
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27 views

Match unpaired points between two sets

I have two sets, let's call them C and T, of unpaired points, which could for example represent two types of cells. Hence, both points are drawn from the same underlying distribution, but the points ...
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59 views

Finding preferences for G-S algorithm (Algorithm Design Chapter 1 exercise 7)

I'm working on Algorithm Design (Kleinberg-Tardos) Chapter 1 exercise 7: Some of your friends are working for CluNet, a builder of large communication networks, and they are looking at algorithms for ...
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27 views

How are matchings a lower bound for an approximate vertex cover?

I am reading Algorithms by Dasgupta et al and they mention maximal matchings as approximations for vertex cover. They mention that the 2-approximation ratio is a lower bound. How is a maximal matching ...
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11 views

Using bloom filters for high speed pattern matching in combination with Aho Corasick

I am implementing a new system for pattern matching in Intrusion Detection Systems for streaming data (network packets). I understand that bloom filters also produce false positives. Is there anyway ...
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61 views

Disjoint groups using maximum matching

In the 3-Path Packing problem, we are given an undirected graph $G$ and a parameter $k \in \mathbb{N} \cup \{0\}$. We need to answer Yes/No if there exists a collection of $k$ vertex disjoint paths on ...
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Find an optimal matching in a complete graph

I have a complete edge-weighted graph with $n$ vertices (and therefore $n\cdot(n-1)/2$ edges). I want to find a complete matching (i.e., perfect matching) in which the quotient $sum_G/A_G$ is maximal, ...
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Stochastic matching with fewer queries

Given a graph $G = (V,E)$ and a probability $p \in [0,1]$ with which each edge is sampled from the graph $G$. The goal of the stochastic matching problem with fewer queries is to find a subgraph $H \...
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146 views

Maximum weight perfect matching in general graphs

Let $G(V,E)$ be a graph (not necessarily bipartite), where edge $e \in E$ has weight $w_e$ (non-negative real). Then one can write the LP relaxation for maximum weight perfect matching as follows $$ \...
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Can somebody please explain what are these variables doing here?

I have this algorithm: I understand overall what's happening here, we're shrinking the blossoms (odd cycles) to end up with a bipartite matching problem, and then opening them again to get a maximum ...
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1answer
184 views

calculating the string similarity of an optimal alignment

description of the algorithms behavior I have two strings s1 and s2, with $len\_s1 <= len\_s2$. I would like to find the ...
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34 views

Is there an approximation algorithm for the three-person stable roommates problem?

While there's an algorithm for solving the stable roommates problem, I understand that the three-people-per-room version of that problem, sometimes called the "threesome roommates problem", ...
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26 views

Matching with specific cardinality

In a weighted graph $G(\mathcal{V},\mathcal{E})$ where $w(i,j)$ is the weight of the edge $(i,j) \in \mathcal{E}$. How can I find a maximum weighted matching with a specific size (i.e specific ...
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68 views

Gale-Shapley Stable matching where one man's preference list changes

Given $n>1$ women and men. Let $M$ be the stable matching given by the Gale-Shapley algorithm with men proposing. Is there a stable matching instance such that: changing one man's preference list ...
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Computing a fractional matching of maximum product in a bipartite graph

Given a bipartite graph $(X\cup Y, E)$ with edge weights, it is easy to find a matching in which the product of weights is maximum: replace each edge weight with its logarithm, and find a matching in ...
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51 views

Maximum matching for general graph

I am studying the maximum matching problem and I was trying to understand why the classical augmenting path algorithm does not work for the general graph (i.e. for non bipartite graph) and you must ...
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1answer
60 views

Can't wrap my head around on building a suffix table for Boyer Moore

My resources were the following video, as well as this video. Basically, in one of the videos they state that the good suffix table for the pattern "ABCBAB" is the following: k suffix d2 1 ...
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1answer
82 views

maximum cardinality weighted matching

I am looking for a reference for maximum cardinality weighted matching and the best running time algorithm for it. Maximum Cardinality Weighted Matching: Given an undirected weighted graph $G(\mathcal{...
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178 views

Find optimal local alignment of two strings with restrictions

I have a homework question that I trying to solve for many hours without success, maybe someone can guide me to the right way of thinking about it. The problem: We want to find an optimal local ...
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63 views

Maximum cardinality matching of maximum weight

Given a graph, I want to find the matching with the maximum size in terms of edges, but among those matchings, given a real weight function on the edges, the one with the maximum weight. Is there an ...
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1answer
25 views

Concept of M-augmenting path to find a larger matching than $M$

I'm reading section 16.1 of the book, Combinatorial optimization, Polyhedra and efficiency by Schrijver. Here, he starts with a matching $M$ and describes a path $P$ that is $M$-augmenting if: The ...
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1answer
31 views

splitting of people betwen groups with group prioritiy list per person

Looking for an algorithm for splitting a list of people (S) into groups (G), |S| <= |G|, more than one person wants to be in a certain group. Every person has a monotone ranking from highest (most ...
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69 views

How difficult is this matching-like problem?

Let $A$ and $B$ be two sets of integers with $|A|>|B|$. Given a map $f: A \rightarrow B$ and $i \in A, j \in B$, let us use the shorthand "$i$ is matched to $j$" if $f(i)=j$. I am ...
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1answer
193 views

Game on the graph with matchings

The game on the graph $G$ is defined as follows. Initially, the chip is located at one of the vertices (let's call it the starting one). The players take turns, on each move it is necessary to move ...
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39 views

Maximal vs maximum matchings

Let $M_1$ be an inclusion-maximal matching in $G$ (that is, there is no matching which strictly contains it), and $M_2$ a maximum-size matching in $G$. How to prove that $|M_2| \le 2|M_1|$?
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45 views

Independent sets into which all the vertices of the graph can be split

How to prove that if $G$ is an acyclic transitive digraph, then the least independent sets into which all vertices of G can be divided is equal to the size of the longest paths to $G$?
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52 views

Maximum one-to-many matching

Let $G = (X+Y,E)$ be a bipartite graph and $k\geq 1$ an integer. A maximum $k$-matching is a subset of $E$ in which each vertex of $X$ is adjacent to at most $k$ edges and each vertex of $Y$ is ...
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56 views

Combinatorial Problem similar in nature to a special version of max weighted matching problem

I have a problem and want to know if there is any combinatorial optimization that is similar in nature to this problem or how to solve this special version of the max weight matching problem. I have a ...
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197 views

Weighted Online Matching - randomized algorithms

Let's consider the edge weighted online matching problem. The Vertices arrive online and reveal all their current edges and edge-weights $w_e>0$. The goal is to maximize the matchings weight. An ...
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90 views

Is there such a problem as b-Matching with different b values?

Consider a bipartite Garph $G=(L \cup R, E)$. Naturally, a b-Matching problem is to find a set of edges $M \subset E$, such that each node in $L$ and $R$ are adjuscent to maximum $b$ neighbors, and a ...
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How to generate a uniform random sample of unique vertex pairings from a undirected graph under constraint?

I'm working on a research project where I have to pair up entities together and analyze outcomes. Normally, without constraints on how the entities can be paired, I could easily select one random ...
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89 views

Are these problems NP-Complete?

I got 2 decision problem that I need to answer if they are in P or they are NP complete: 1.Just like subset sum: given the integers or natural numbers ${\displaystyle w_{1},\ldots ,w_{n}}$ does ...
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33 views

Stable matching with dynamic preference lists

I have a set $F$ of $n_1$ families, a set $C$ of $n_2$ children ($n_1<n_2$) and a set $M$ of feasible one-to-one matchings of the families with the children. All the children have the same ...
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Blossom Algorithm

I have noticed that in the blossom algorithm, we need to find the blossom while finding the augmenting path. What will happen if I just know there is a blossom in a graph and the contracted graph has ...
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69 views

Special case of stable marriage

I have an instance of the stable marriage problem in which the first side $S_1$ has $n_1$ agents and the second side $S_2$ has $n_2$ agents with $n_2$ is very big in comparison to $n_1$. In addition, ...
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118 views

Options for approaching stable marriage problem with unequally sized sets of elements/preferences

I am looking for an algorithm/code that will provide stable matching for two unequally sized sets of elements (clubs and students) with an unequal set of preferences. There is a large pool of students ...
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1answer
87 views

Selecting k rows and k columns from a matrix to maximize the sum of the k^2 elements

Suppose $A$ is an $n \times n$ matrix, and $k \ge 1$ is an integer. We want to find $k$ distinct indices from $\{1, 2, \ldots, n\}$, denoted as $i_1, \ldots, i_k$, such that $\sum_{p, q = 1}^k A_{...
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Algorithm for b-matching on bipartite graph [duplicate]

I have a bipartite graph, where I want to assign nodes in Left set to Right set of nodes. There is a "b" constraint, which limits the maximum possible node degrees on the Right set. Since it is a ...
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104 views

Best and Worst options in Gale Shapley algorithm for an agent

Please consider the figure below. I have to find the best and worst options for W. From the preference list of W, the best option for W is D but there is no matching of W with D in all the 6 options. ...
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183 views

An algorithm to find the closest match between 2 arrays of RGB pixel tuples

So I'm looking for a bit of an abstract algorithm and I'd appreciate any references to read up on. This is a bit tough to explain but I'll try my best. Suppose we have 2 arrays of ...